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Old 21st May 2007, 05:00 PM   #91
PMA is offline PMA  Europe
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Hi lineup,

actually not much space left, dimensions are 38 x 22 x 7 cm (15" x 8.7" x 2.75" - for US readers), and 225VA Talema toroidal transformer inside.
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Old 21st May 2007, 06:57 PM   #92
fotios is offline fotios  Greece
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Quote:
Originally posted by PMA
My newly designed power amp:
Hi PMA
It is very good and clear construction. I have only one question. The power transformer and the PCBs don’t need ventilation? I don't see airing slots (notches) or holes in the top cover.
Fotios
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Old 21st May 2007, 07:33 PM   #93
PMA is offline PMA  Europe
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You are right, they do not need vent holes. In this specific case. I do not try to generalize.
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Old 24th May 2007, 01:45 AM   #94
HKC is offline HKC  Hong Kong
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My all JFet line stage pre-amp.
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File Type: jpg rimg0020.jpg (97.3 KB, 6692 views)
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Old 25th May 2007, 11:50 PM   #95
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Good show!

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Old 26th May 2007, 03:06 AM   #96
jleaman is offline jleaman  Belgium
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Here is one of my chassis, this holds 2 Aleph Mini a's 20watts class a each. One chassis per speaker, so i can bi-amp.

Jase

Click the image to open in full size.
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Old 26th May 2007, 02:06 PM   #97
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Quote:
Originally posted by PMA
Hi lineup,

the amp has MOSFET output stage, and in principle is based on "Difference of 2 squares". The output stage has gain of 4. You can tell more from the attached image.

I have not tested it with the mentioned signal yet.
Hi Pavel,

Very nicely built! Is it a real D2S amp, as described by Ian Hegglun in EW+WW, 1995?
BTW, you do like exotic topologies, don't you. (nothing wrong with that!)

Cheers, Edmond.
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Old 26th May 2007, 02:22 PM   #98
lineup is offline lineup  Sweden
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Quote:
Originally posted by jleaman

Here is one of my chassis,
this holds 2 Aleph Mini a's 20watts class a each.
One chassis per speaker, so i can bi-amp.

Jase
.

Great Solid construction - and using Master Nelson's circuits.

Bi-amping is the Ultimate Way!
Many good things from true, 2 amplifiers per loudspeaker, biamping.



This is my final goal:
- Build 2 two-ways loudspeakers
- Drive each woofer with it's own Power amplifier = 4 endstage mono amplifiers
Maybe some day come true .... I hope.


One simple way, is to build it using 4 x LM3875 National Power IC amps.
These modules are put inside loudspeaker box.
Then I need one stereo preamplifier with volume control
and some signal cables to feed loudspeaker + amplifier modules.
And a clever way, to switch POWER ON to my complete setup.


If dreams could make wishes come True
- this is what I would really would do



Regards - and thanks for your nice image, jleaman
lineup
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Old 26th May 2007, 03:28 PM   #99
PMA is offline PMA  Europe
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Quote:
Originally posted by estuart


Hi Pavel,

Very nicely built! Is it a real D2S amp, as described by Ian Hegglun in EW+WW, 1995?
BTW, you do like exotic topologies, don't you. (nothing wrong with that!)

Cheers, Edmond.
Hi Edmond,

basically, yes. Semptember 1995 issue, Fig.2. R3 and R4 resistors are replaced by current sources, that are connected to supply rails. This has improved noise background at lower frequencies and stability. The opamp voltage gain stage is placed in front of the original circuit and the output stage gain is reduced to 4x. There is a global NFB. And yes, I like the bright circuit ideas

Regards,
Pavel
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Old 26th May 2007, 04:08 PM   #100
jleaman is offline jleaman  Belgium
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Quote:
Originally posted by lineup



Great Solid construction - and using Master Nelson's circuits.

Bi-amping is the Ultimate Way!
Many good things from true, 2 amplifiers per loudspeaker, biamping.



This is my final goal:
- Build 2 two-ways loudspeakers
- Drive each woofer with it's own Power amplifier = 4 endstage mono amplifiers
Maybe some day come true .... I hope.


One simple way, is to build it using 4 x LM3875 National Power IC amps.
These modules are put inside loudspeaker box.
Then I need one stereo preamplifier with volume control
and some signal cables to feed loudspeaker + amplifier modules.
And a clever way, to switch POWER ON to my complete setup.


If dreams could make wishes come True
- this is what I would really would do



Regards - and thanks for your nice image, jleaman
lineup
Lineup Audio Labs

Thank's for the kind words :P

Im bi-amping these :
Click the image to open in full size.

and switching between these.

Click the image to open in full size.
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